<?php

defined('BASEPATH') OR exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 5.1.6 or newer
 *
 * @package        CodeIgniter
 * @author        EllisLab Dev Team
 * @copyright    Copyright (c) 2006 - 2012, EllisLab, Inc.
 * @license        http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since        Version 1.0
 * @filesource
 */
// ------------------------------------------------------------------------

/**
 * Migration Class
 *
 * All migrations should implement this, forces up() and down() and gives
 * access to the CI super-global.
 *
 * @package        CodeIgniter
 * @subpackage    Libraries
 * @category    Libraries
 * @author        Reactor Engineers
 * @link
 */
class CI_Migration {

    protected $_migration_enabled = FALSE;
    protected $_migration_path = NULL;
    protected $_migration_version = 0;
    protected $_error_string = '';

    public function __construct($config = array()) {
        # Only run this constructor on main library load
        if (get_parent_class($this) !== FALSE) {
            return;
        }

        foreach ($config as $key => $val) {
            $this->{'_' . $key} = $val;
        }

        log_message('debug', 'Migrations class initialized');

        // Are they trying to use migrations while it is disabled?
        if ($this->_migration_enabled !== TRUE) {
            show_error('Migrations has been loaded but is disabled or set up incorrectly.');
        }

        // If not set, set it
        $this->_migration_path == '' AND $this->_migration_path = APPPATH . 'migrations/';

        // Add trailing slash if not set
        $this->_migration_path = rtrim($this->_migration_path, '/') . '/';

        // Load migration language
        $this->lang->load('migration');

        // They'll probably be using dbforge
        $this->load->dbforge();

        // If the migrations table is missing, make it
        if (!$this->db->table_exists('migrations')) {
            $this->dbforge->add_field(array(
                'version' => array('type' => 'INT', 'constraint' => 3),
            ));

            $this->dbforge->create_table('migrations', TRUE);

            $this->db->insert('migrations', array('version' => 0));
        }
    }

    // --------------------------------------------------------------------

    /**
     * Migrate to a schema version
     *
     * Calls each migration step required to get to the schema version of
     * choice
     *
     * @param    int    Target schema version
     * @return    mixed    TRUE if already latest, FALSE if failed, int if upgraded
     */
    public function version($target_version) {
        $start = $current_version = $this->_get_version();
        $stop = $target_version;

        if ($target_version > $current_version) {
            // Moving Up
            ++$start;
            ++$stop;
            $step = 1;
        } else {
            // Moving Down
            $step = -1;
        }

        $method = ($step === 1) ? 'up' : 'down';
        $migrations = array();

        // We now prepare to actually DO the migrations
        // But first let's make sure that everything is the way it should be
        for ($i = $start; $i != $stop; $i += $step) {
            $f = glob(sprintf($this->_migration_path . '%03d_*.php', $i));

            // Only one migration per step is permitted
            if (count($f) > 1) {
                $this->_error_string = sprintf($this->lang->line('migration_multiple_version'), $i);
                return FALSE;
            }

            // Migration step not found
            if (count($f) == 0) {
                // If trying to migrate up to a version greater than the last
                // existing one, migrate to the last one.
                if ($step == 1) {
                    break;
                }

                // If trying to migrate down but we're missing a step,
                // something must definitely be wrong.
                $this->_error_string = sprintf($this->lang->line('migration_not_found'), $i);
                return FALSE;
            }

            $file = basename($f[0]);
            $name = basename($f[0], '.php');

            // Filename validations
            if (preg_match('/^\d{3}_(\w+)$/', $name, $match)) {
                $match[1] = strtolower($match[1]);

                // Cannot repeat a migration at different steps
                if (in_array($match[1], $migrations)) {
                    $this->_error_string = sprintf($this->lang->line('migration_multiple_version'), $match[1]);
                    return FALSE;
                }

                include $f[0];
                $class = 'Migration_' . ucfirst($match[1]);

                if (!class_exists($class)) {
                    $this->_error_string = sprintf($this->lang->line('migration_class_doesnt_exist'), $class);
                    return FALSE;
                }

                if (!is_callable(array($class, $method))) {
                    $this->_error_string = sprintf($this->lang->line('migration_missing_' . $method . '_method'), $class);
                    return FALSE;
                }

                $migrations[] = $match[1];
            } else {
                $this->_error_string = sprintf($this->lang->line('migration_invalid_filename'), $file);
                return FALSE;
            }
        }

        log_message('debug', 'Current migration: ' . $current_version);

        $version = $i + ($step == 1 ? -1 : 0);

        // If there is nothing to do so quit
        if ($migrations === array()) {
            return TRUE;
        }

        log_message('debug', 'Migrating from ' . $method . ' to version ' . $version);

        // Loop through the migrations
        foreach ($migrations AS $migration) {
            // Run the migration class
            $class = 'Migration_' . ucfirst(strtolower($migration));
            call_user_func(array(new $class, $method));

            $current_version += $step;
            $this->_update_version($current_version);
        }

        log_message('debug', 'Finished migrating to ' . $current_version);

        return $current_version;
    }

    // --------------------------------------------------------------------

    /**
     * Set's the schema to the latest migration
     *
     * @return    mixed    true if already latest, false if failed, int if upgraded
     */
    public function latest() {
        if (!$migrations = $this->find_migrations()) {
            $this->_error_string = $this->line->lang('migration_none_found');
            return false;
        }

        $last_migration = basename(end($migrations));

        // Calculate the last migration step from existing migration
        // filenames and procceed to the standard version migration
        return $this->version((int) substr($last_migration, 0, 3));
    }

    // --------------------------------------------------------------------

    /**
     * Set's the schema to the migration version set in config
     *
     * @return    mixed    true if already current, false if failed, int if upgraded
     */
    public function current() {
        return $this->version($this->_migration_version);
    }

    // --------------------------------------------------------------------

    /**
     * Error string
     *
     * @return    string    Error message returned as a string
     */
    public function error_string() {
        return $this->_error_string;
    }

    // --------------------------------------------------------------------

    /**
     * Set's the schema to the latest migration
     *
     * @return    mixed    true if already latest, false if failed, int if upgraded
     */
    protected function find_migrations() {
        // Load all *_*.php files in the migrations path
        $files = glob($this->_migration_path . '*_*.php');
        $file_count = count($files);

        for ($i = 0; $i < $file_count; $i++) {
            // Mark wrongly formatted files as false for later filtering
            $name = basename($files[$i], '.php');
            if (!preg_match('/^\d{3}_(\w+)$/', $name)) {
                $files[$i] = FALSE;
            }
        }

        sort($files);
        return $files;
    }

    // --------------------------------------------------------------------

    /**
     * Retrieves current schema version
     *
     * @return    int    Current Migration
     */
    protected function _get_version() {
        $row = $this->db->get('migrations')->row();
        return $row ? $row->version : 0;
    }

    // --------------------------------------------------------------------

    /**
     * Stores the current schema version
     *
     * @param    int    Migration reached
     * @return    bool
     */
    protected function _update_version($migrations) {
        return $this->db->update('migrations', array(
                'version' => $migrations
        ));
    }

    // --------------------------------------------------------------------

    /**
     * Enable the use of CI super-global
     *
     * @param    mixed    $var
     * @return    mixed
     */
    public function __get($var) {
        return get_instance()->$var;
    }

}

/* End of file Migration.php */
/* Location: ./system/libraries/Migration.php */